What is virus?/ structure of virus.
1. The central substance in the center is the nucleic acid (either DNA or RNA, not both). The central nucleic acid or nucleic acid region surrounded by the capsid may be called the nucleoid nucleus.
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2. The capsid or protein coat surrounds the central body. The arrangement of protein molecules in the capsid controls the arch-shape of the virus. The capsid consists of a number of subunits with protein molecules arranged to form a rod-shaped helix and spherical polyhedron structure. The subunits are called capsomeres. The number and type of capsomeres vary among different viruses. The outer coat of the capsid can be smooth or barbed with spines called spikes.
3. Some viruses have another coat outside the capsid, usually 10-15 pm thick, known as the envelope.
Chemical structure of viruses: Chemically, viruses are mainly composed of two types of material, namely: Nucleic acid (core material) and capsid (protein).
1. Nucleic acid (core) : Nucleic acid located in the center of the virus. In certain viruses the nucleic acid is either DNA or RNA. DNA and RNA never coexist. In other organisms, DNA and RNA coexist. Generally most plant viruses contain RNA and most animal viruses contain DNA. But this is not applicable in all cases.
2. Capsid (Protein): Capsid is made up of protein molecules. Capsids are generally biologically inactive. The main function of capsids is to protect nucleic acids, but they also aid in host infection. In particular, capsids contain proteins along with lipids and starches. The capsid protects the internal material (DNA or RNA) and also acts as an antigen. It induces sneezing in colds
3. Outer coat: Some viruses (eg influenza virus, herpes virus, HIV, corona virus etc.) have a coat of organic material outside the capsid. It is chemically composed of lipids, lipoproteins, carbohydrates, or lipids. 9 units of lipids or lipoproteins are called pelpomeres. Lipoprotein coated viruses are called lipoviruses.
